This is a very good question. In order to be able to answer this question completely, your physician will need to take a thorough history focused on your ears (Hx of hearing loss, ear surgery
, noise exposure, etc) and also perform a thorough exam.
Without having that information (particularly what your ears look like), it is hard to gauge exactly the extent of what will need to be done to your ears. Otoplasty is a term that is used to describe surgery to alter or reconstruct completely the pinna (outer part of the ear). Other then aesthetic appearance, the pinna's general function is that of a funnel to collect sound waves and direct them down the external auditory canal for hearing. Although in a strict sense it does impact hearing, the exact amount is hard to quantify. In fact some patients that have lost their pinna altogether maintain good hearing without significant impairment.
I cannot tell for sure, but you didn't mention anything like microtia (congenitally small or deformed pinna), or anotia (absent pinna), so I am assuming that you will have a more minor cartilage shaping procedure done. So the likelihood of this affecting your hearing to any significant degree should be very low. Nonetheless I would recommend having a good conversation with your surgeon
about your concerns. Hope this helps.